Packetized data networks typically format data into packets for transmission from one site to another. In particular, the data is partitioned into separate packets at a transmission site, wherein the packets usually include headers containing information relating to packet data and routing. The packets are transmitted to a destination site in accordance with one or more data transmission protocols, where the transmitted data is recoverable from the received packets. Tags can be inserted into packets for a variety of purposes. For example, tags can be used for forwarding classification of packets, such as utilized in Multiprotocol Label Switching (MPLS), in which packet-forwarding decisions are made based solely on the contents of a packet label without having to examine the packet itself. This allows the ability to create end-to-end circuits across different types of transport media, using any protocol.
Tags also can be used for traffic segmentation, such as the use of IEEE Standard 802.1q protocol Virtual Local Area Network (VLAN) tags. For example, a VLAN tag signifying VLAN 4 or VLAN 322 indicates a particular VLAN route for the packet. Additionally, tags can be used for network service orchestration, such as the Cisco Service Insertion Architecture (SIA) tag for service insertion and chaining, or network security, such as the Cisco Security Group Tag (SGT).
These tagging technologies generally require that all network devices between the tag encapsulation and the tag decapsulation nodes of the packet path must be able to process and/or preserve network tags. To take advantage of a particular network tag technology, it may be necessary to upgrade all network devices across at least some portion of a network. The substantial cost associated with such a network upgrade may discourage early adoption of the network tag technology and deprive subscribers of its benefits.